Polyimides have been widely used, for example, in the field of electronic communication and OA appliances as well as in the field of aerospace because they have excellent heat resistance among a variety of organic polymers. In particular, the polyimides have recently been desired to have not only excellent heat resistance but also a variety of performance for a wide range of uses.
Photosensitive polymers can be obtained by a reaction of existing polymers and photosensitive groups functioning as pendant groups. A representative example of the photosensitive polymers prepared by this method is polyvinyl cinnamate invented by Minsk et al., which is disclosed in J. Appl. Polymer Sci., 2, 302 (1959). Polyvinyl cinnamate is prepared by the esterification of polyvinyl alcohol using cinnamic acid chloride. This polymer is irradiated with light to form cyclobutane rings to be cross-linked and cured.
However, to the inventors' knowledge, polyimides with a derivative of cinnamoyl skeleton joined to their side chains is reported only in Japanese Unexamined Patent Publication No. (Patent Kokai No.)55-45747 (1980). The polyimide disclosed in the Patent Kokai No. 55-45747 contains, as a diamine monomer component, aromatic diamine in which an amino group and one or two photosensitive group(s) such as cinnamic acid derivative are bonded to the same aromatic residue.
Although a polymer into which a reactive group having a double bond or triple bond is introduced may be used as thermosetting resins, there have been few cases where polyimides are used as thermosetting resins by introducing such thermoreactive group thereto.
Furthermore, although an increase in number of reactive groups per polymer repeating unit increases a cross-linking density and improves properties, there have been few cases where polyimide contains a multifunctional diamine as a monomer component.
An object of present invention is to provide a diamine and an acid dianhydride which have a reactive group containing a double bond or triple bond so as to exhibit both photoreactivity and thermoreactivity specific to the reactive group, and a polyimide containing the diamine and the acid dianhydride as monomer components.